The present invention relates to a printing press with a plate making unit for performing plate making for a plate mounted on a plate cylinder in a printing unit.
Generally, when performing plate making for a plate, it is required to increase the efficiency of plate making operation and to eliminate the space where a plate making unit is to be installed. Hence, in recent years, a plate making unit independent of the printing press is not provided, but a plate making unit added to the printing press itself performs plate making directly on the printing press. More specifically, a plate before plate making is mounted on a plate cylinder in a printing unit, and the plate making unit is moved to abut its head against the plate cylinder. Subsequently, the plate cylinder is rotated, and simultaneously the head is moved in the axial direction of the plate cylinder, thereby performing plate making for the plate. When the plate is to be supplied/removed or maintenance is to be performed, the plate making unit is separated from the printing unit.
In the conventional printing press described above, the plate making unit positioned at an operative position where plate making can be performed disturbs plate change operation. To prevent this, in plate change operation in which an old plate mounted on the plate cylinder is removed and a new plate is mounted on the plate cylinder, the plate making unit is moved to separate from the printing unit. However, in some cases, an operator changes a plate in a state wherein the plate making unit is not moved or is not separated enough to change the plate, and this may damage the plate or the plate making unit.
It is an object of the present invention to provide a printing press which prevents the plate making unit from damage or the surface of the plate from scratch.
In order to achieve the above object, according to the present invention, there is provided a printing press comprising a plate cylinder having an outer surface on which a plate is mounted, a plate making unit for performing plate making for the plate mounted on the outer surface of the plate cylinder, the plate making unit being supported to be movable between an operative position where plate making is performed and a wait position to escape from the operative position, detection means for detecting the plate making unit positioned at the wait position, and control means for controlling plate change operation in accordance with a detection output from the detection means.